Fuser - Epson EPL-N3000 Service Manual

EPSON EPL-N3000/AcuLaser M4000N

2.5.5 FUSER

HEAT ROLL
This hollow surface-coated metal tube, heated by the Heater Rod located therein,
applies heat to the paper passing between this roll and the Pressure Roll. This heat
fuses the toner on the paper.
PRESSURE ROLL
This metal shaft, coated with sponge rubber, applies pressure to the paper between this
roll and the Heat Roll. This pressure presses the molten toner against the paper.
HEATER ASSEMBLY
Consists of the Heater Rod, which is a lamp comprising a heat coil contained in a
sealed quartz glass pipe, and the terminal installed from the end of the Heater Rod via
the harness. The Heater Rod is located in the Heat Roll, and the Heat Roll gets heated.
TEMPERATURE SENSOR
This sensor is a thermistor whose resistance varies in a known value according to
temperature change. This sensor, installed in contact with the surface of the Heat Roll,
monitors the temperature. Using the signal from this sensor, the power to the Heater
Rod is turned on and off so that the surface temperature of the Heat Roll is maintained
within the rated range. This signal is also used for the first-stage overheat prevention.
THERMOSTAT SENSOR (STS)
Two STSs are installed. The STSs are connected in series with the Heat Roll, and
function as overheat prevention in the second stage. If the overheat of the fuser cannot
be prevented in the first stage, the STSs open the power supply circuit of the Heater
Rod. The functions of the STSs are as described below.
To prevent the Pressure Roll from seizing up by wrong setting of paper, the STS
opens the power supply circuit to cool it down when the detected temperature rises
to or above the preset temperature.
To prevent both edges of paper from curling caused by a temperature rise on both
sides of the Heat Roll, the STS lights up the Short lamp to control a temperature
rise when the detected temperature rises to or above the preset temperature.
Operating Principles
HEAT ROLL FINGERS
Peels the leading edge of the paper off the Heat Roll so that the paper does not wind
around the Heat Roll.
HEAT ROLL DIODE
Negative charge is accumulated on the Heater Rod. This charge can disturb the toner
image on the paper during fusing. The Heat Roll Diode dissipates this charge into the
frame for grounding.
EXIT SENSOR
Detects the arrival of the paper at the detecting point of the outlet area behind the Fuser
and ejection of the paper from there.The /EXIT signal turns low when the sensor is
receiving light (there is paper).
Figure 2-29. Major Components of the FUSER&PAPER EXIT
Functions of Major Components
Revision C
Exit Sensor
Actuator
Temperature Sensor
Pressure Roll
Heat Roll
Thermostat Sensor
G6122EA
Confidential
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